Elasticity and anisotropy of iron‐nickel phosphides at high pressures
Elasticity and anisotropy of iron‐nickel phosphides at high pressures
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DOI：
10.1029/2011gl049158
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发表时间：
2011-10
影响因子：
5.2
通讯作者：
Xiang Wu;M. Mookherjee;T. Gu;S. Qin
中科院分区：
文献类型：
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作者：
Xiang Wu;M. Mookherjee;T. Gu;S. Qin
地球化学估计表明，地球上大约90%的磷可能被封存在地核中。磷化铁，如辉石（Fe3P），通常在铁陨石中发现。近年来，在铁陨石中发现了磷含量为12.2wt %的铁镍矿（Fe,Ni）4P。通过静态电子结构计算，我们预测在内核条件下，Fe4P不可能解离成Fe3P和hcp Fe。在不同的Fe4P结构变体中，我们发现具有P213空间群对称性的三次晶型在大范围的物理相关压力下是稳定的。在高达400gpa的压力下，我们确定了稳定的（Fe,Ni）4P相的状态方程和全弹性常数张量。压缩后，Fe4P在80gpa下经历铁磁性（fm）到非磁性（nm）的转变。在非磁性（Fe,Ni）4P中，镍的掺入导致P波和S波速度的降低。然而，镍的掺入增强了P波和S波的各向异性。
Geochemical estimates indicate that around 90% of the planet's inventory of phosphorus is likely to be sequestered in the Earth's core. Iron phosphides such as scheirbisites (Fe3P) are commonly found in iron meteorites. Recently, melliniite (Fe,Ni)4P with 12.2 wt% phosphorus has been reported in iron‐meteorites. Using static electronic structure calculations, we predict that Fe4P is unlikely to dissociate into Fe3P and hcp Fe at inner core conditions. Among the different structural varieties of Fe4P, we find the cubic polymorph with P213 space group symmetry to be stable over a wide range of geophysically relevant pressures. We have determined the equation of state and the full elastic constant tensor of the stable (Fe,Ni)4P phase at pressures up to 400 GPa. Upon compression, Fe4P undergoes a ferromagnetic (fm) to nonmagnetic (nm) transition at 80 GPa. In nonmagnetic (Fe,Ni)4P, nickel incorporation results in reduction of the P‐ and S‐wave velocities. However, incorporation of nickel enhances the P‐ and S‐wave anisotropy.